Plastics may be processed by various molding methods and are essential materials in our lives. In particular, among the plastics, thermoplastic resins are excellent in flexibility and are widely used. On the other hand, the strength or rigidity of a thermoplastic resin is not necessarily sufficient in some cases. For example, in an application that requires high strength and high rigidity, a thermoplastic resin is reinforced by incorporating, into the thermoplastic resin, a short fiber of an inorganic fiber such as a glass fiber or a carbon fiber. Patent Document 1 discloses an organic fiber-reinforced composite material constituted by an ultrahigh molecular weight polyethylene fiber and a methacrylate-based vinylester resin for the purpose of improving the shock absorptivity and rigidity.
Patent Document 2 discloses an automobile bonnet which includes an outer part made of an FRP and an inner part joined to the rear side of the outer part. It is described that performances related to pedestrian protection are enhanced by such an FRP automobile bonnet.
Patent Document 3 discloses a composite body of a sandwich structure in which a fiber-reinforced material constituted by a continuous fiber and a matrix resin is provided on both of a core material. The core material is formed with a through hole in the thickness direction and the fiber-reinforced materials are joined to each other by the matrix resin at the through hole. It is described that the composite body with such a sandwich structure is suitable for a housing of an electric or electronic device such as a portable information terminal since it is thin, light and highly rigid. However, it is doubtful whether a shock resistance required for application to a vehicle is provided.    (Patent Document 1) JP-A-6-126847    (Patent Document 2) WO 2006/025316    (Patent Document 3) JP-A-2009-220478